A coalition of ministers and same-sex marriage opponents formally requested a citywide referendum yesterday to block the District from recognizing gay marriages performed in other jurisdictions, setting the stage for a heated legal and political battle over the issue this summer.

In paperwork filed with the D.C. Board of Elections and Ethics, the group Stand 4 Marriage D.C. said it wants to begin the process of collecting about 21,000 signatures needed to overturn the bill that the D.C. Council overwhelmingly approved this month recognizing same-sex marriages performed elsewhere. That bill is tentatively scheduled to take effect in July.

The referendum effort is a preemptive strike designed to slow plans by several council members to take up a separate bill this year to allow same-sex marriages to be performed in the District.

"It's a declaration of war," said Bishop Harry Jackson, senior pastor of Hope Christian Church in Beltsville, a vocal critic of same-sex marriage and a leader of the referendum effort. "We are sending a clear message this is going to be fought every step of the way."

Jackson has allied with other ministers from the Washington region. The Archdiocese of Washington issued a statement yesterday reiterating its opposition to same-sex marriage but withheld support for the proposed referendum until church officials could review it.

Jackson said same-sex marriage opponents are buoyed by the decision Tuesday by the California Supreme Court to let stand that state's referendum last year against same-sex marriage. Jackson noted that voters in almost 30 other states have supported ballot proposals opposing same-sex marriage.

Same-sex marriage opponents in the District face a greater hurdle to get the issue on the ballot than opponents did in California, where it is common for questions to land before voters. Moments after Jackson's filing was made, supporters of same-sex marriage vowed they would push to keep the issue off a ballot.

"Civil rights shouldn't be subject to referendum," said council member Phil Mendelson (D-At Large), who sponsored the bill to recognize same-sex marriages performed elsewhere.

Before opponents can start collecting signatures, the Board of Elections must decide whether the question of overturning Mendelson's bill qualifies to be on a ballot.

If approved, the referendum could be put to voters in a special election this year or next or in next year's council and mayoral elections.

Under D.C. election law, referendums cannot be used to appropriate funds, overturn a budget act or violate the Human Rights Act. Mark Levine, a lawyer and gay rights activist, said he's confident that Mendelson's bill falls under the Human Rights Act. He said the elections board would be "engaged in an extraordinary act of lawlessness" if it allows the referendum to move forward.

"The D.C. government cannot discriminate on the basis of sexual orientation, and for them to recognize marriages of straight couples and not to recognize marriages of gay couples would be a clear violation of the Human Rights Act," Levine said.

A spokesperson for the elections board did not return calls yesterday. Jackson said he is willing to pursue the matter in court if the board rejects his application.

If the board approves the application, opponents will have 180 days to meet the requirements of a referendum, which involves collecting signatures from at least 5 percent of the registered voters in at least five of the city's eight wards. That has proved to be a formidable task in previous referendum efforts.

In 2004, supporters of slot machine gambling in the District failed to get their referendum on the ballot after thousands of signatures were deemed invalid.

If an election were held, gay rights activists said, they think they could defeat the measure.

Noting the District's progressive reputation, Mendelson said he thinks "the sentiment of the community is pretty clear" in support of same-sex marriage.

"In the District, you got 55 percent African American, a growing number of Hispanics, an immigrant community that is by and large not pro-gay marriage," Jackson said.

Philip Pannell, an African American gay rights activist who lives in Ward 8, said that Jackson is misreading the local black community.

"It's a different electorate" than in California, Pannell said. "We have a much more activist black, gay and lesbian community here in D.C., and they will step up and speak out and organize against it. But it will be a struggle."